1. What is the missing angle, x?
130° x°

2. Trace the diagram and turn it upside down
130°
50°

3. Trace the diagram and turn it upside down
130°
50°

4. What is angle y?
How do you know?
130°
50° y°

5. What is angle z?
How do you know?
130°
50° z°

6. a° b° c° d° Angles a and d are equal. They are vertically opposite.
Angles b and c are equal. They are vertically opposite. a° b° c° d°

7. Find the missing angles. Give a reason for your answer.
On your whiteboards:
Find the missing angles. Give a reason for your answer.
40°
140° a° b°
38°
150°
135° c° d°

9. What have they done wrong?
40°
140° a°
a = 40°
because vertically opposite angles are equal
How can you show that they are wrong?

10. Let’s trace the whole shape this time, and translate the tracing along one of the lines.
130°
50°
50°
130°

11. Let’s trace the whole shape this time, and translate the tracing along one of the lines.
130°
50°
50°
130°

12. What are the missing angles?
130°
50° a° b°
50°
130° c° d°
Which lines are parallel?
How do you know they are parallel?

13. Trace the whole shape, and translate the tracing along one of the lines.
35°

14. Let’s trace the whole shape this time, and translate the tracing along one of the lines.
35°

15. What are the missing angles?
Which lines are parallel?
How do you know they are parallel?
35° c° d° b° a°

16. Title: Angles in parallel lines.
Find all of the missing angles.

17. Challenge
If this angle is x°, what are the sizes of all the other angles in the diagram?
If this angle is (y + 30)°, what are the sizes of all the other angles in the diagram?